imageio v3 api fails to read all frames in a MetaMorph stk file

The following zip file contains a single .stk image stack (https://support.moleculardevices.com/s/article/MetaMorph-Software-TIFF-and-STK-file-formats) with 2 frames: test.zip (I zipped it because github doesn’t support uploading stks but does support zips…) imageio v2 volread reads it fine, but the v3 API only sees the first frame:

In [17]: imageio.volread("test.stk").shape
Out[17]: (2, 290, 364)

In [18]: imageio.v3.imread("test.stk", index=...).shape
Out[18]: (1, 290, 364)

In [19]: len([*imageio.v3.imiter("test.stk")])
Out[19]: 1

(Note that stk files are explicitly listed as supported by the tifffile module.)

[anntzer]

Here is a small stk file that I hereby allow you to add to the test suite of imageio: movie.zip.

[FirefoxMetzger]

The Molecular Devices support said that they don’t believe that there is any licence that applies to the images and that they “make them available and assume that they will be used for positive applications”. I asked for clarification regarding the online terms of use that @cgohlke found.

In the interest of not stalling for too long, I will go ahead and merge #805 with a regression test that xfails until we have clarity about the applicable copyright.